THE SOUTHWESTERN NATURALIST 52(1):75–78 MARCH 2007 RESPONSE OF MARSH RICE RAT (ORYZOMYS PALUSTRIS) TO INUNDATION OF HABITAT ALISA A. ABUZEINEH,* ROBERT D. OWEN, NANCY E. MCINTYRE, CARL W. DICK, RICHARD E. STRAUSS, AND TYLA HOLSOMBACK Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409 Present address of AAA: Aquatic Station, Department of Biology, Texas State University, San Marcos, TX 78666 *Correspondent: firstname.lastname@example.org ABSTRACT—Although the swimming behavior of Oryzomys palustris has been described, little is known about how long this species will remain in an area that is inundated by several centimeters of water. This study documents the responseof an O. palustris population to habitat inundation in a coastal prairie locality of southeastern Texas. During a mark-recapture study conducted during 2002 and 2003, we livetrapped O. palustris on a grid in an area that experienced prolonged ($5 mo) inundation during 2 of our 6 quarterly trapping periods. We describe a trapping technique, using foam rafts to support rodent live-traps, that is suitable for use in inundated areas. Despite long-term inundation, little available refuge, and an apparent complete turnover of the population, we estimated population densities of ca. 29 individuals per hectare during inundation, only a moderate decrease from the higher levels encountered before and after inundation. RESUMEN—A pesar de que se ha descrito el comportamiento natatorio de Oryzomys palustris, se sabe poco sobre cuanto tiempo permanece esta especie en un área inundada por varios centímetros de agua. Esta investigación documenta la respuesta de una población de O. palustris a la inundación de hábitat en un llano costero del sureste de Texas. Durante un estudio de marca-recaptura realizado durante el 2002 y el 2003, capturamos vivos los O. palustris, en una parcela de un área que sufrió inundación prolongada ($5 meses), durante 2 de nuestras 6 sesiones trimestrales de trampeo. Describimos una técnica de trampeo usando balsas de unicel para sostener trampas para roedores, que son útiles para usar en áreas inundadas. A pesar de la prolongada inundación, la falta de refugio disponible y un aparente cambio completo de la población, estimamos una densidad poblacional de aproximadamente 29 individuos por hectárea durante la inundación, sólo una moderada disminución del nivel más alto encontrado antes y después de la inundación. Oryzomys palustris is a medium-sized (adult weight 45 to 80 g) semi-aquatic murid rodent (Wolfe, 1982a). It has a long tail and large hind feet with partially webbed toes that facilitate propulsion while swimming (Esher et al., 1978). The species occurs in marshy areas or along bodies of water from southern coastal Texas, northeast along the Gulf of Mexico to Florida, and in riparian habitats as far north as Kansas and Maryland (Wolfe, 1982a; Kays and Wilson, 2003). Esher et al. (1978) suggested that the water-resistant properties of the pelage play an important role in the ability of the ratto maintain its body temperature and buoyancy, and they noted its ability and tendency to dive and swim up to 10 m underwater when startled. During our field research, we witnessed the diving behavior described by (Esher et al., 1978), but the pelage seemed to become saturated within a few seconds. Wolfe (1982b) examined the effects of storms on ricerats in a coastal marsh in Mississippi. He sampled populations before and after 3 storm events that produced high tides and strong winds for a few hours. He concluded that, although populations were smaller following storms, the impact probably was not serious (Wolfe, 1982b). Despite what is known regarding the ecology and swimming ability of the species and the effects of short-term inundation, little is known regarding how long O. palustris will remain in a flooded area. In this paper, we examine the effects of long-term inundation (ca. 6 mo) on a population of O. palustris in coastal southeastern Texas.